DATETIME Default Value: NOW() or '0000-00-00 00:00:00'?

Default Value for Datetime Datatype: NOW() or '0000-00-00 00:00:00'?

To set the default value for datetime datatype, you can consider the following options:

Current Default Value: '0000-00-00 00:00:00'

• This is the default value used by MySQL for datetime columns without an explicit default.
• You can modify an existing table to set this value with the following SQL statement:

ALTER TABLE users MODIFY lastVisitDate datetime DEFAULT '0000-00-00 00:00:00';

Dynamic Default Value: NOW()

• From MySQL version 5.6.5 onwards, you can use a dynamic default value to set the datetime to the current time:

CREATE TABLE users (
    registerDate datetime DEFAULT CURRENT_TIMESTAMP
);

• You can also modify an existing table with a DATETIME column to use NOW() as the default:

ALTER TABLE users MODIFY registerDate datetime DEFAULT CURRENT_TIMESTAMP;

Note: Prior to MySQL 5.6.5, dynamic default values for datetime were not supported. You could use the TIMESTAMP datatype instead, but it only allowed one auto-updated timestamp column per table.

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